"FILE – In this Sept. 18, 2018 file photo, Sen. Rob Portman, R-Ohio, stops to answer questions for members of the media as he returns to a hearing on Capitol Hill in Washington. Portman said the United States shouldn't let North Korea ""off the hook"" for its treatment of a college student who died soon after his release. The Republican senator has been in contact with Otto Warmbier's family since the suburban Cincinnati youth was imprisoned in early 2016 for allegedly stealing a propaganda banner. He died in June 2017 after returning in a vegetative state. His parents say he was tortured.  (AP Photo/Pablo Martinez Monsivais, File)"